In the processing of tubular knitted and other types of fabrics, there is a continuing trend toward processing at higher speeds, for greater operating efficiency. In the processing of tubular knitted fabrics, for example, there have been important improvements made in the rate of speed at which the fabric may be steamed and calendered, as reflected in the Frezza U.S. Pat. No. 3,875,624. As processing speeds have increased, some difficulties have been experienced in the subsequent gathering of the processed fabric. Where the fabric is to be gathered in roll form, the higher operating speeds are accommodated by employing improved arrangements for removing of filled rolls and restarting of winding of a new roll, as for example set forth in the Frezza U.S. Pat. Nos. 3,941,326 and 3,944,149. However, where the fabric is to be gathered by folding, different kinds of problems are presented by high speed operation.
In a typical fabric folder, the fabric is directed through a fabric guide, which may include a pair of closely spaced, oppositely rotating rollers. The fabric guide is oscillated back and forth at controlled speed, above a receiving platform, causing the fabric to be deposited in successive layers of substantially uniform length.
Where folding is carried out at conventional, relatively low speeds (typically on the order of 30-45 yards per minute) conventional folding equipment functions effectively. However, as speeds are increased to fifty yards per minute and above, significant problems begin to arise as a result of the necessity of moving a broad expanse of fabric laterally, in a direction substantially normal to its principal plane. When the oscillating guide reverses directions and accelerates, the broad expanse of fabric tends to become "plastered" against one side of the guide, interferring with the free downward movement of the fabric under gravity. Where this downward movement is required to occur at high speeds, even minor inhibiting of fabric movement can have a significant and undesirable effect on the folding operation, resulting in unacceptable variation in the length of individual folded layers and other problems.
In accordance with one of the significant aspects of this invention, the oscillating guide means is provided in the form of a pair of opposed panels, constructed in permeable form and joined to a plenum chamber containing air under low pressure. During operation of the folder, air is constantly flowing at low velocity through the front faces of the opposed panels. In general, the air flowing through the panels serves to provide a cushion effect, and is not utilized to impel the fabric in a downward direction. As the fabric guide oscillates back and forth, one or the other of the opposed panels functions to "push" the fabric broad side over the folding area. By reason of the cushion of air issuing from the front face of the panels, the fabric is prevented from actually contacting the panels, at least to any substantial extent. With the system of the present invention, fabric is reliably discharged from the lower end of the folding guide at a highly uniform rate, even at extremely high rates of speed. For example, whereas conventional folding equipment is largely limited to speeds of well under fifty yards per minute, the method and apparatus of the present invention enable fabric to be folded at a rate of eighty and sometimes even one hundred yards per minute.